There have been proposed various aspects of an exhaust heat recovery device that performs a heat exchange between exhaust gas discharged from an internal combustion engine and a heat exchange medium. An exhaust heat recovery device disclosed in Patent Literature 1 described below adopts a configuration in which a plurality of cylindrical members is disposed to form an inner space where a sound muffling mechanism is formed and an outer space where a heat exchanger is disposed. This exhaust heat recovery device is configured such that when an on-off valve disposed on a downstream side of the inner space is closed, exhaust gas flows into the outer space to exchange heat with a heat exchange medium in the heat exchanger and then flows out to a downstream side. Meanwhile, when the on-off valve is opened, the exhaust gas flows into the inner space and then flows out to the downstream side without exchanging heat.
An exhaust heat recovery device disclosed in Patent Literature 2 described below adopts a configuration in which a plurality of cylindrical members is disposed to form an inner space and an outer space where a heat exchanger is disposed. This exhaust heat recovery device is configured such that when a shutoff valve disposed on a downstream side of the inner space is closed, exhaust gas flows into the outer space to exchange heat with a heat exchange medium in the heat exchanger and then flows out to a downstream side. Meanwhile, when the shutoff valve is opened, the exhaust gas flows into the inner space and then flows out to the downstream side without exchanging heat.
Further, the heat exchanger disclosed in Patent Literature 2 described below is formed with a tube laminate in which a plurality of flat tubes each formed as a tube having a pair of cutout portions in which an upper and a lower portion of a hollow, flat, circular donut shape are linearly cut out, is laminated to overlap with each other. This tube laminate is fitted to a case with an exhaust inflow side end plate and an exhaust outflow side end plate. A cutout portion provided on the exhaust inflow side end plate is disposed to correspond to one of the cutout portions of the tube laminate. Further, a cutout portion provided on the exhaust outflow side end plate is disposed to correspond to the other cutout portion of the tube laminate.
In the exhaust heat recovery device disclosed in Patent Literature 2 described below, the shutoff valve is closed during warming up of an internal combustion engine, the exhaust gas flows out from one of the cutout portions to the tube laminate side and flows through a gap between the respective flat tubes from the top to the bottom as a whole. When the exhaust gas flows in, the heat exchange medium flows inside the respective flat tubes from the bottom to the top as a whole to exchange heat with the exhaust gas, and the exhaust heat is recovered.